Case head separation due to FL resizing brass?

[Deleted member 107796]

the first time it happened it was on Remington brass and maybe 5 or 6 firings.

The most recent one was on federal brass and I was on my 4th firing. I was resizing the brass just enough to load in the gun but when I pulled tried to pull the brass out complete head separation. I count my self lucky because I feel sure it would have stuck in the gun. The brass was super thin where it pulled off.
On the other hand...
I've got some nosler brass thats on my 7th firing. The brass looks good but I'll be honest I'm going to file it away for war time. Little gun shy now on the brass after so many firing. Done set up and been slowly prepping new brass now. Man I hate the new brass prep. Just ain't taking the chance. I'm still trying to save my die by getting the brass out.

RCBS used to take these out for about a $10 shipping fee.

 

[J E Custom]

Both Belted or shouldered cases can/will have case head separation if not sized correctly or to much. The tighter the space between the case head and the bolt with the round seated against the shoulder the better. Case stretch is the culprit and anything that can reduce it will help prevent head separation.

To be honest, I have never "Bumped" a shoulder when a partial full length sizing was all it took to chamber the round without altering the case length. Different brands of cases will last a different number of firings, but improper sizing or over sizing will reduce the number of firings of any brass case. Belted case are the most notorious for case head separation because if sized the way they were intended to be there is lots of clearance between the shoulder of the chamber and the shoulder of the case if head spaced on the belt.

Improper sizing is normally the biggest cause of this problem.

J E CUSTOM

 

[Vol1975]

Both Belted or shouldered cases can/will have case head separation if not sized correctly or to much. The tighter the space between the case head and the bolt with the round seated against the shoulder the better. Case stretch is the culprit and anything that can reduce it will help prevent head separation.

To be honest, I have never "Bumped" a shoulder when a partial full length sizing was all it took to chamber the round without altering the case length. Different brands of cases will last a different number of firings, but improper sizing or over sizing will reduce the number of firings of any brass case. Belted case are the most notorious for case head separation because if sized the way they were intended to be there is lots of clearance between the shoulder of the chamber and the shoulder of the case if head spaced on the belt.

Improper sizing is normally the biggest cause of this problem.

J E CUSTOM

this last episode of case head failure I pre measured everything like I always do and measured several times throughout the process. I was adjusting or Playing with the die so that when I was bumping things back just enough so that it would close in the bolt fairly easy. When I was done the shoulders went back roughly .002 maybe 4 depending on the particular piece and the area right above the belt went back .003 ths.
.513 to .510 ths. This measurement was checked on numerous cases. there was no other sighs of any problems with the case that I personal could see.
im just chalking it up to case life end personally. Maybe a better brass I could get better life than federal but I think going forward at 4 firing I'm getting rid of the brass. Been reloading for a long time and the only time I've had this problem is when I've used FL resize on brass that was a little old.

I just personally think with older brass and the way it pushes the brass back around the belt it causes a stress in older brass around this area. but this has been my experience.

 

[BallisticsGuy]

If you have to bump .002 to get the bolt to close then something is massively wrong. If it were necessary to bump .002" you'd never be able to open the bolt in the first place. talking about bumping .004 . .002 is a huge amount.

Stop bumping your shoulders, start neck sizing only. Use dye-chem if needed to figure out where things do need to be sized. You are reducing your brass life by not paying attention to the high quality free advice that you're being given.

 

[bigedp51]

Look at the SAAMI cartridge and chamber drawing below and how much the headspace and belt can vary.

It is your head clearance and how much you bump the shoulder back that governs how far the case can stretch when fired.

Below is a example of a British .303 military Enfield rifle, and at max headspace of .074 and a rim thickness of .058 you would have .016 head clearance. And a big difference from only bumping the shoulder back .001 to .002.

And once the case has been fired and only neck sized the case headspaces on its shoulder and not its rim or belt. If you full length resize with the die making hard contact with the shell holder you will allow the case to stretch by the variation in rim or belt thickness and the rifles headspace.

 

[J E Custom]

Cases that head space on the shoulder can have zero head space and the bolt will still close. Ideally, you want .0005 to .0015 maximum to be able to shoot all factory ammo.

If you load, you can hold the head space @ .0000 and still be able to close the bolt. If you neck size only the head space will remain .0000 in your chamber for a while and then only "slight" sizing will be required to close the bolt. My best case life with any brand has been when I maintain a tight fit and can close the bolt with very slight resistance to maintain complete support for the case during firing.

Some cartridges with 15o to 20o shoulders can tolerate .004 to .006 compression from the bolt caming over without causing chambering problems.

Again, with belted cases the first time they are fired they will stretch the most after that, the stretch is managed with minimum sizing. With full length sizing of a belted case, 3 or 4 loading's is about all you can expect from any brand.

J E CUSTOM

 

[Vol1975]

If you have to bump .002 to get the bolt to close then something is massively wrong. If it were necessary to bump .002" you'd never be able to open the bolt in the first place. talking about bumping .004 . .002 is a huge amount.

Stop bumping your shoulders, start neck sizing only. Use dye-chem if needed to figure out where things do need to be sized. You are reducing your brass life by not paying attention to the high quality free advice that you're being given.

Ok, so I could always could get the bolt to close on the fired brass it was just a little tight. It was just a little tight after the brass was fired more than likely from my darn fault of pushing the pressure to the upper limits. I recognize that even thou I was still showing no ejector marks and slightly primers that were being flattened. Again I only bump thing back just enough for hunting purpose to have the bolt close Very easy. Typically when I'm done my goal when comparing a fire formed brass to the brass piece that I bumped has a reduced measurement of rougly .002 th of difference from the shoulder area and around the belt. Some may be .001 more here or their. I use the proper tools, gauges, mic, etc just like I have done the past 30 years of reloading. Heck I've even checked as I do with all my guns with a go and no go gauge.

Now as far as neck sizing I've done the neck size thing 20 years ago and all it takes during a hunting season is a little crude and u can't close the darn thing. Thus why I bump thing back Just enough for the bolt to close easy.
Finally I take people advice like JE custom very serious. Their is great advice from people on this forum. Nothing beats experience and nothing beats learning from other people mistakes and success.

I do appreciate all the comments good and bad from people. People on this site are by far the most helpful people that I've seen in my 50 years of hunting and shooting.

 

[XTR]

I reload about 2000+ rounds a yr for competition all of them are FL sized. I've not had a case head seperation in close to 8 yrs, and that was because I was shooting the brass in 2 different chambers. That doesn't happen any more since I started buying my own reamers.

Here is a trick for you. Take your new brass, be it factory ammo or reloads with new brass, shoot it once. Now take that fired brass and adjust your die down till you bump the shoulder, then adjust it out till you get 0.000 change in the shoulder. Lock the die there till you re-barrel.

Once fired brass, unless you are dropping nuclear loads, will have sprung back some, not much but enough that if you size to that demin you will be good.

 

[BallisticsGuy]

OP: You need to get yourself one of these http://www.larrywillis.com/

 

[WalksLikeADeer]

this last episode of case head failure I pre measured everything like I always do and measured several times throughout the process. I was adjusting or Playing with the die so that when I was bumping things back just enough so that it would close in the bolt fairly easy. When I was done the shoulders went back roughly .002 maybe 4 depending on the particular piece and the area right above the belt went back .003 ths.
.513 to .510 ths. This measurement was checked on numerous cases. there was no other sighs of any problems with the case that I personal could see.
im just chalking it up to case life end personally. Maybe a better brass I could get better life than federal but I think going forward at 4 firing I'm getting rid of the brass. Been reloading for a long time and the only time I've had this problem is when I've used FL resize on brass that was a little old.

I just personally think with older brass and the way it pushes the brass back around the belt it causes a stress in older brass around this area. but this has been my experience.[/QU
I use Remington brass in 7mm Rem Mag, anneal after every firing, Redding body die and Lee collet neck size at max book loads(no pressure signs) and have around 10-12 firings. I retired the brass not because of any signs but just because I thought I should. Primer pockets were still tight as always with Rem brass.

What is your annealing process and how much over book max are your loads?

 

[WalksLikeADeer]

so. This has happened twice now and tell me what you guys or gals think.

First about 10 years ago I FL resized some Remington brass (7mm mag) and when I reshot this brass I had several case head brass spilts right above the belt. Luckily was able to extract from gun. I stoped what I was doing and basically threw the brass out. I chalked it up to older brass and when I resized the brass I stressed the brass by FL resizing it back down to Sammy specs.
For a long time I never had a problem again but I didn't use the FL dye a lot either. Mostly shot a 06 with lower pressure and a ton of new brass. Anyway...

So fast forward to this weekend.
Hornady brass and 7mm again. Now this brass has had about 3-4 firings when I had a total case head separation. Again luckily I screwed up a dye instead of a gun. Anyway. Brass stuck in dye when I was bumping shoulders back .001 th.
Where it failed was right above the belt. Lube was plenty and the amount I reduce next to the belt was approximately .002-.003. I will admit I run top speed and pressure on this round so this could be a factor.
So my question is 2 folds. Is their a cut off limit that one follows on the amount of brass is shot. And 2 does the FL resizing dye that one uses stress the brass enough to promote failure in this manner.
Anyway Im pretty careful on measurements and how much I'm bumping stuff back. so this has happened twice now has gave me concern on using older brass and FL dyes in these magnums.
Closing. Trashed all older brass at this point and backing off a grain on my load.

Any thoughts?

 

[WalksLikeADeer]

I use Remington brass in 7mm Rem Mag, anneal after every firing, Redding body die and Lee collet neck size at max book loads(no pressure signs) and have around 10-12 firings. I retired the brass not because of any signs but just because I thought I should. Primer pockets were still tight as always with Rem brass.

What is your annealing process and how much over book max are your loads?

 

[Vol1975]

I use Remington brass in 7mm Rem Mag, anneal after every firing, Redding body die and Lee collet neck size at max book loads(no pressure signs) and have around 10-12 firings. I retired the brass not because of any signs but just because I thought I should. Primer pockets were still tight as always with Rem brass.

What is your annealing process and how much over book max are your loads?

I anneal after 2 firings. I have been using the Larry Willis die for several years on the body and then using the Forster dye for bumping the shoulders back .002ths. Doing this I have not had a problem.
now fast forward I retried the FL resize die And achieved basically the same thing measurement wise. The problem is when I've done this on older brass is where I have had the problem. My personally thought process is that the way the FL die pushes back on the brass above the belt it stresses the brass in this area on brass that has been used a fair amount. Brass old and thinner and probably brittle. Anyway just my thought. I have since retired the brass and will use my Larry Willis die going forward.

pressure wise my primers are just starting to flatten but not ejector marks. . I'm pushing 175gr eld approx 2920fps.

 

[WalksLikeADeer]

I anneal after 2 firings. I have been using the Larry Willis die for several years on the body and then using the Forster dye for bumping the shoulders back .002ths. Doing this I have not had a problem.
now fast forward I retried the FL resize die And achieved basically the same thing measurement wise. The problem is when I've done this on older brass is where I have had the problem. My personally thought process is that the way the FL die pushes back on the brass above the belt it stresses the brass in this area on brass that has been used a fair amount. Brass old and thinner and probably brittle. Anyway just my thought. I have since retired the brass and will use my Larry Willis die going forward.

pressure wise my primers are just starting to flatten but not ejector marks. . I'm pushing 175gr eld approx 2920fps.